Process for preparing a polymer from allyloxytrifluoropropenes

ABSTRACT

A process for preparing a polymer comprising the step of: polymerizing:
         (i) an allyloxytrifluoropropene derivative selected from the group consisting of compounds represented by the formula:       

       CF 3 CH═CH(OCH 2 CR═CH 2 ); 
       CF 3 CH═C(OCH 2 CR═CH 2 ) 2 ; 
       CF 3 CH═CF(OCH 2 CR═CH 2 ); and          any mixtures thereof; wherein R is selected from the group consisting of: hydrogen and methyl; and optionally   (ii) an ethylenically unsaturated comonomer;
 
wherein the copolymerizing step is carried out in the presence of a catalyst, under conditions sufficient to produce the copolymer.

CROSS-REFERENCE TO A RELATED APPLICATION

The present application is a Divisional Application of U.S. patent application Ser. No. 11/900,081 filed on Sep. 10, 2007, and claims priority from U.S. Provisional Application No. 60/843,934, filed Sep. 12, 2006, the contents of which are incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a process for making allyloxytrifluoropropenes and homopolymers and copolymers thereof starting from fluoro olefins. More particularly, the present invention relates to a process for making compounds, such as, CF₃CH═CHOCH₂CH═CH₂, CF₃CH═CFOCH₂CH═CH₂, CF₃CH═C(OCH₂CH═CH₂)₂ and methallyl derivatives thereof from CF₃CH═CHF or CF₃CH═CF₂ and allyl or methallyl alcohol.

2. Description of the Prior Art

Compounds containing allyloxy group are typically used as monomers for preparing siloxane polymers or as a CF₃ building block. See, for example, Polymer Chemistry, (1995) 33(14), 2415-23, J. Polymer Sci. A: Polym. Chem (1997) 35, 1593-1604 and Chem. Commun., (1996), 57-58.

Uses of polymers derived from allyl ethers for UV curing, to films on various surfaces, for adhesives, coating, cladding and the like are described in J. Polym. Sci., Part A, Polym. Chem., 2002, 40, 2583-2590.

Allyloxypropene of the formula CF₃CH₂CFHOCH₂—CH═CH₂ is used as a monomer for making siloxane polymers, as described in the German Patent DE 3,138,235 A1 and in J. Fluorine Chem., (2005), 126, 281-288.

Relatively little is known about allyloxypropene polymers in general. U.S. Pat. No. 6,930,159 B1 describes some fluorinated allyl ether polymers. However, the structure of monomers used in the preparation of the polymers described in this patent is quite different from the allyloxypropene monomers described in the present invention.

Relatively little is known about allyloxypropenes described by the present invention. The only known example in this group is 1-allyloxy-3,3,3-trifluoropropene of the formula CF₃CH═CH(OCH₂CH═CH₂) which is made from CF₃CBr═CH₂ with a base and catalytic amount of water.

This reaction proceeds by an elimination-addition mechanism through the formation of trifluoromethylpropyne as an intermediate followed by the addition of allyl alcohol to the so formed trifluoromethylpropyne (See Chem. Commun., (1996), 57-58).

However, large-scale preparation of allyloxytrifluoropropenes using this approach requires the use of CF₃CBr═CH₂ as a starting material, which is expensive and cumbersome to manufacture.

Compounds such as CF₃CH═C(OCH₂CH═CH₂)₂ with two allyloxy groups and polymers derived therefrom are unknown in the art.

Consequently, there is a need in industry to develop commercially feasible processes for making such compounds and exploring their properties and uses in various applications.

To achieve this objective, the present invention provides a process, which is practical and, as such, it is potentially useful commercially.

SUMMARY OF THE INVENTION

The present invention provides a process for the preparation of an allyloxytrifluoropropene derivative represented by the formula:

CF₃CH═CR¹(OCH₂CR═CH₂)

wherein:

R¹ is selected from hydrogen, fluoro, and allyloxy group represented by the formula:

—OCH₂CR═CH₂

wherein R is hydrogen or methyl.

The process includes the steps of:

contacting:

(i) a compound represented by the formula:

CF₃CH═CR²R³

wherein R² is selected from the group consisting of hydrogen, chloro, and fluoro and wherein R³ is chloro or fluoro; and

(ii) an allyl alcohol derivative represented by the formula:

HOCH₂CR═CH₂

wherein R is hydrogen or methyl;

wherein the contacting is carried out in the presence of a base and optionally a solvent at a temperature and length of time sufficient to produce the allyloxytrifluoropropene derivative.

The present invention further provides allyloxytrifluoropropene derivatives, including compounds of the following formula:

CF₃CH═C(OCH₂CH═CH₂)₂;

CF₃CH═C(OCH₂C(CH₃)═CH₂)₂;

CF₃CH═CH(OCH₂C(CH₃)═CH₂); and

CF₃CH═CF(OCH₂CR═CH₂);

wherein R is hydrogen or methyl.

The present invention still further provides process for preparing a polymer including the step of:

polymerizing:

(iii) an allyloxytrifluoropropene derivative selected from compounds represented by the formula:

CF₃CH═CH(OCH₂CR═CH₂);

CF₃CH═C(OCH₂CR═CH₂)₂;

CF₃CH═CF(OCH₂CR═CH₂); and

any mixtures thereof;

wherein R is hydrogen or methyl; and optionally

(iv) an ethylenically unsaturated comonomer;

wherein the copolymerizing step is carried out in the presence of a catalyst, preferably including methylphenylsilane and CO₂(CO)₈, under conditions sufficient to produce the copolymer.

The present invention also provides homopolymers and copolymers of these allyloxytrifluoropropene derivatives prepared by the polymerization process according to the present invention.

The process according to the present invention is practical and, as such, it is potentially useful commercially.

These and other benefits of the present invention will become more evident from detailed description of the preferred embodiments that follow.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

When CF₃CH═CF₂ is reacted with allyl alcohol or methallyl alcohol at 25° C. to 35° C. with catalytic amount of a base, such as, Cs₂CO₃, in a polar solvent, quite unexpectedly, the major product formed was the fluoride substitution produce, rather than the expected product of addition to the carbon-carbon double bond, to form CF₃CH═C(OCH₂—CH═CH₂)₂ (IA).

Even with only catalytic amount of a base being present, both of the vinylidene fluorines in CF₃CH═CF₂ can be replaced by allyloxy group. This is an unknown reaction of vinylidene fluorides and, as such, it is an unexpected reaction.

Temperature appears to play an important role in these reactions. At lower temperatures, such as, for example, at temperatures from about 20° C. to about 5° C., one can predominantly obtain the addition product of the formal CF₃CH₂CF₂OCH₂—CH═CH₂ (IC).

In contrast, when a temperature from about 25° C. to about 35° C. is used, the major product formed is CF₃CH═C(OCH₂—CH═CH₂)₂ (IA); the minor being CF₃CH═CF(OCH₂—CH═CH₂) (IB) (˜5 to 20%) as shown in Scheme 1 below. Thus, under these experimental conditions, only trace amount of the expected addition product (IC) was seen.

This above reactions are depicted in the Scheme 1 below.

In large scale preparations, the volatiles generated in the reaction can be trapped in a cold trap/scrubber and thereafter neutralized and the HF generated can be neutralized via washing with aqueous NaOH solution.

Alternately, if the exclusive preparation of IA is desired, one can employ two equivalents of base to neutralize the HF generated during the reaction.

As mentioned before, the reparation of Compound IIA CF₃CH═CH(OCH₂CH═CH₂) has been reported in the literature using a method which employs CF₃CBr═CH₂ as a starting material.

This approach is described in greater detail in Chem. Commun., 1996, 57-58 and is depicted in Scheme 2 herein below.

In the present invention, this problem can be overcome by the use of commercially available CF₃CH═CHF with a base, as depicted in Scheme 3 below.

Alternately, CF₃CH═CHCl can also be used in place of CF₃CH═CHF which is commercially available. Typically, bases such as Cs₂CO₃, K₂CO₃, and sodium or potassium tertiary butoxide can be used in Schemes 1 and 2.

The starting material CF₃CH═CHF can be made in large scale from commercially available CF₃CH₂CF₂H according to methods described in U.S. Pat. No. 6,548,719 B1. CF₃CH₂CF₂H is produced by and is available from Honeywell International, Inc., Morristown, N.J.

Preferably, CF₃CH═CF₂ is formed from CF₃CH₂CF₂H by chlorination followed by dehydrochlorination and CF₃CH═CHF is formed from CF₃CH₂CF₂H by dehydrofluorination.

The step of contacting is carried out at a temperature sufficient to produce the allyloxytrifluoropropene derivative. Contacting is preferably carried out at a temperature of about 25° C. to about 100° C., more preferably about 25° C. to about 50° C., and most preferably about 25° C. to about 35° C.

The step of contacting is carried out at a pressure sufficient to produce the allyloxytrifluoropropene derivative. Contacting is preferably carried out at a pressure of about 0.5 to about 1 atm and most preferably about 1 atm.

The step of contacting is carried out for a length of time sufficient to produce the allyloxytrifluoropropene derivative. Contacting is preferably carried out for a length of time of about 5 minutes to about 300 hours, more preferably about 30 minutes to about 5 hours, still more preferably about 30 minutes to about 2 hours, and most preferably about 2 hours.

The step of contacting is preferably carried out at a temperature from about 25° C. to about 50° C., at a pressure of about 0.5 atm to about 1 atm, and for a length of time from about 30 minutes to about 5 hours.

More preferably, the step of contacting is carried out at a temperature from about 25° C. to about 35° C., at a pressure from about 1 atm, and for a length of time from about 30 minutes to about 2 hours.

The process can be either a batch process or it can be a continuous process.

The reactor can further include a diluent, such as, a solvent or mixture of solvents. Preferably, polar, non-protic solvents, such as, acetonitrile, dimethylformamide (DMF), dimethylsulfoxide (DMSO), are used as the reaction medium. However, other solvents, such as, mono- and di-ethers of glycols, mono- and di-esters thereof, glymes, diglymes, triglymes, and tetraglymes can also be employed.

The process can further include one or more of the following steps:

(1) isolating the product from the reaction mixture by pouring the crude reaction mixture onto cold water at about 5° C. whereby the product separates out the lower layer; and

(2) purifying the reaction product via distillation under reduced pressure to obtain the product in substantially pure form.

In operation, preferably at least 10 wt % of the reactants are converted to the product. More preferably, up to at least 80 wt % of the reactants are converted to the product, and most preferably, at least 90 wt % of the reactants are converted to the product. Accordingly, operation of the process of the present invention under high conversion conditions is preferred.

Polymerization can be carried out essentially the same way as the methods known and described in the art, such as, the methods described in J. Polymer Sci. A: Polym. Chem. (1997) 35, 1593-1604 and U.S. Pat. No. 6,930,159 B1. Thus, both monomers can be readily polymerized to form homopolymers under standard polymerization conditions known to a person skilled in the art.

Alternatively, these monomers can be also readily polymerized to copolymers if an ethylenically unsaturated comonomer is present.

Depending on the polymerization conditions, the polymers can be obtained as transparent or white powders.

The allyloxytrifluoropropenes according to the present invention are suitable for use as monomers in the preparation of polymers and copolymers, including preparation of coatings, and particularly UV cured coatings.

The following non-limiting examples are illustrative of the various embodiments of the present invention. It is within the ability of a person of ordinary skill in the art to select other variable from amongst the many known in the art without departing from the scope of the present invention. Accordingly, these examples shall serve to further illustrate the present invention, not to limit them.

EXPERIMENTAL DETAILS

Unless otherwise indicated, all parts and percentages are on a weight basis.

Example 1 1,1-Bis-allyloxy-3,3,3-trifluoropropene (CF₃CH═C(OCH₂CH═CH₂)₂)

To a stirred mixture of acetonitrile (100 mL), allylalcohol, CH₂═CHCH₂OH, (20 g, 0.34 mol) and catalytic amount cesium carbonate (1.5 g, 4.6 mmol) was added, CF₃CH═CF₂ (0.40 mol) via a gas sparger. The addition of CF₃CH═CF₂ was such that the temperature of the reaction was not more than 36° C. After complete addition (30 minutes), the reaction mixture was stirred for 1 hour, poured into 400 mL cold water, mixed well and the upper layer was separated. Separated organic layer was mixed with water (400 mL), allowed to settle. The lower layer was separated, washed with water (50 ml), dried (MgSO₄) and filtered to afford crude product CF₃CH═C(OCH₂CH═CH₂)₂. Pure product was obtained on distillation under reduced pressure (50 to 55° C./8-9 mm Hg) as a colorless liquid (25 g, 35% yield).

The structure of the product is consistent with the following spectroscopic data:

GC/MS data: m/e 208 (M⁺ for C₉H₁₁F₃O₂);

¹⁹F NMR (CDCl₃) δ=−68.6 (3F, d, J_(HF)=8 Hz) ppm; and

¹H NMR (CDCl₃) δ=5.87 (1H, m), 5.71 (1H, m), 5.36-5.09 (4H, m), 4.65 (2H, dt, J=6 and 2 Hz), 3.2 (1H, m), 2.6 (2H, m) ppm.

The other product formed in this reaction is CF₃CH═CF(OCH₂CH═CH₂).

Example 2 1-Allyloxy-3,3,3-trifluoropropene (CF₃CH═CH(OCH₂CH═CH₂))

To a stirred mixture of acetonitrile (240 mL), allylalcohol, CH₂═CHCH₂OH, (20 g, 0.34 mol) and sodium tertiarybutoxide (34.5 g, 0.36 mol) was added, CF₃CH═CFH via a gas sparger. The addition CF₃CH═CFH was such that the temperature of the reaction was not more than 35° C. After complete addition (about 45 minutes), the reaction mixture was stirred for 1 hour, poured into 400 mL cold water, mixed well and the upper layer was separated. Separated organic layer was mixed with water (400 mL), allowed to settle. The lower layer was separated, washed with water (50 ml), dried (MgSO₄) and filtered to afford 42 g product characterized to be CF₃CH═CHOCH₂CH═CH₂, which was 86% pure, by GC. Pure product was obtained on distillation under reduced pressure (36 to 42° C./68 mm Hg) to afford the pure product as a colorless liquid (32 g, yield=62%). The ratio of cis- to trans-isomer is 96:2.

The structure of the product is consistent with the following spectroscopic data:

GC/MS data: m/e 152 for M⁺ (M=C₆H₇F₃O);

NMR data for trans: ¹⁹F NMR (CDCl₃), δ=−59.1 (3F, m) ppm; and

¹H NMR (CDCl₃) δ=7.03 (1H, dq, overlaps J=12 and 2 Hz), 5.92 (m, 1H), 5.28-5.40 (m, 2H), 5.0 (1H, dq, overlaps, J=12 and 6 Hz) and 4.3 (2H, dm, J=5 Hz) ppm.

Example 3

The reaction was carried out in the same manner as described in the Example 2 except that CF₃CH═CHCl was used in place of CF₃CH═CHF. CF₃CH═CHOCH₂CH═CH₂ was obtained in 50% yield.

Example 4 Polymerization of CF₃CH═CH(OCH₂CH═CH₂)

Polymerization was conducted essentially the same way as described in J. Polymer Sci. A: Polym. Chem. (1997) 35, 1593-1604.

To a clean vial containing a Teflon coated magnetic stirbar and a Teflon backed septa was added 15 mg (4.5×10⁻⁵ mol) of CO₂(CO)₈ in an Argon-filled dry box. To this was added 2.6 mL of dry Toluene followed by 20 uL (1.1×10-4 mol) of dry diphenylsilane. This was mixed, and, after 15 minutes, the 1-allyloxy-3,3,3-trifluoropropene (0.65 mL, 5.0×10⁻³ mol) was added via syringe. The vial was placed on a hot plate at 110° C. for 2 hrs while stirring. The reaction was quenched with a few drops of triethylamine (TEA) and then the polymer was precipitated in methanol. The polymer was then dried under vacuum at 80° C. for overnight.

The remaining polymer was determined by ¹H, ¹⁹F NMR to contain the CH₃ groups in the main chain with characteristic broad peaks associated alkyl CH groups and phenyl silyl peaks as endgroups along with characteristic CF₃ groups. The resulting polymer was shown by GPC using polystyrene standards to have a MW=2,171 (weight average molecular weight) and Dp=3.01 (degree of polymerization).

Example 5 Polymerization of CF₃CH═C(OCH₂CH═CH₂)₂

Polymerization is conducted in essentially the same manner as in Example 3, with the exception that CF₃CH═C(OCH₂CH═CH₂)₂ was used instead of 1-allyloxy-3,3,3-trifluoropropene.

The present invention has been described with particular reference to the preferred embodiments. It should be understood that variations and modifications thereof can be devised by those skilled in the art without departing from the spirit and scope of the present invention. Accordingly, the present invention embraces all such alternatives, modifications and variations that fall within the scope of the appended claims. 

1. A process for preparing a polymer comprising the step of: polymerizing: (i) an allyloxytrifluoropropene derivative selected from the group consisting of compounds represented by the formula: CF₃CH═CH(OCH₂CR═CH₂); CF₃CH═C(OCH₂CR═CH₂)₂; CF₃CH═CF(OCH₂CR═CH₂); and any mixtures thereof; wherein R is selected from the group consisting of: hydrogen and methyl; and optionally (ii) an ethylenically unsaturated comonomer; wherein said copolymerizing step is carried out in the presence of a catalyst, under conditions sufficient to produce said copolymer.
 2. The process of claim 1, wherein said catalyst comprises methylphenylsilane and CO₂(CO)₈.
 3. The process of claim 1, where said allyloxytrifluoropropene derivative is: CF₃CH═C(OCH₂CH═CH₂)₂ 